Electric motor drive system and method

ABSTRACT

An electric motor system and method are shown having a circuit board arranged in a plane that lies in a predetermined angle relative to an axis to an armature of the electric motor. In one embodiment the predetermined angle is an acute angle and the plane is not perpendicular to an axis of an armature of the motor  10.  Brushes are located remotely from the board.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a commutator motor drive gear systemand method and more particularly to a motor having a circuit board thatit lies in a plane that is not perpendicular to an axis of the drivemotor.

[0003] 2. Description of Prior Art

[0004] In the past, printed circuit boards comprised circuits forcontrolling electrical motors, such as window lift motors, seat drivemotors and other electrical motors that are used in vehicles. It hasbeen convenient to situate the circuit board near the motor. U.S. Pat.No. 5,528,093 discloses integrating electronics with a drive unit. Aprinted-circuit board, which accommodates the electronic components andwhich is designed, at the same time, as a brush-holder plate for thecommutator motor, is arranged, together with an electronic housing,parallel to housing flanges of a motor housing of a gear housing. Theprinted circuit board of the drive unit is covered on its one axial sideby the motor housing and the electronic housing and on its other axialside by the gear housing, thereby protecting it from external elements.

[0005] With the arrangement disclosed in the prior art U.S. Pat. No.5,528,093, the circuit board in situated in a plane that isperpendicular to an axis of the drive motor so that the brushes, whichare mounted directly on the circuit board, are situated in operativerelationship with the commutator of the electric motor. One problem withthis arrangement was that the circuit board had to be alignedperpendicular to the axis of the armature of the electric motor so thatthe brushes could be properly aligned with the commutator.

[0006] Another problem with the prior art designs is that when thebrushes were situated on the board which required that the board besituated on a plane, which was substantially perpendicular to the axisof the armature. A longer armature and/or redesign of the commutator orbrush holders would be needed if the board was not situated in a plane,perpendicular to the axis of the armature of the electric motor.

[0007] What is needed therefore is a simplified design that is capableof accommodating different motor and brush arrangements and that willpermit a circuit board to be situated in a plane that is notperpendicular to an axis of an armature of an electric motor.

SUMMARY OF THE INVENTION

[0008] It is a primary object of the invention to provide an electricmotor having a shaft and printed circuit board comprising a circuit forcontrolling the motor, where the printed circuit board is generallyplaner and lies in a plane that bisects an axis of the armature at apredetermined angle that is not perpendicular to the axis of thearmature and where the brushes are not mounted directly on the board.

[0009] In one aspect, this invention comprises an electrical motorhaving a shaft, the electrical motor comprising a motor housing having apair of permanent magnets situated in opposed relation therein a rotorsituated on the shaft between the pair of permanent magnets the rotorcomprising a plurality of windings situated thereon a commutator forpassing current to the plurality of windings, a printed circuit boardcomprising a circuit for controlling the motor the printed circuit boardbeing generally planar and lying in a first plane that bisects the axisto define at least one predetermined angle that is acute, a pair ofbrushes situated in a brush housing in operative relationship with thecommutator, a pair of conductors coupling the pair of brushes to theprinted circuit board and a plurality of terminals situated on theprinted circuit board for coupling the circuit to a power source.

[0010] In another aspect, this invention comprises a drive unitcomprising, an electrical motor having a shaft having a first gear, theelectrical motor comprising, a motor housing having a pair of permanentmagnets situated in opposed relation therein, a rotor situated on theshaft between the pair of permanent magnets the rotor comprising aplurality of windings situated thereon, a commutator for passing currentto the plurality of windings, a printed circuit board comprising acircuit for controlling the electrical motor; the printed circuit boardbeing generally planar, a pair of brushes situated in a brush housing inoperative relationship with the commutator, a pair of conductorscoupling the pair of brushes to the printed circuit board, a pluralityof terminals situated on the printed circuit board for coupling theprinted circuit board to a power source, a gear housing comprising asecond gear rotatably mounted therein and situated in operativerelationship to the first gear; and the printed circuit lying in a firstplane and being mounted between the motor housing and the gear housingsuch that the first plane bisects the axis at a predetermined angle.

[0011] And still another aspect, this invention comprises a method forassembling an electrical motor having a shaft comprising an axis, arotor having a plurality of windings, and a commutator for passingcurrent to the windings, the method comprising the steps of providing amotor housing having a pair of permanent magnets situated in opposedrelation therein situating the rotor between the pair of permanentmagnets, situating a printed circuit board in a first plane that bisectsthe axis to define a predetermined angle, the printed circuit boardcomprising a circuit and a plurality of terminals for coupling thecircuit to a power source, providing a pair of brushes in a brushhousing in operative relationship with the commutator, but remote fromthe printed circuit board and coupling the pair of brushes to theprinted circuit board.

[0012] Other objects and advantages of the invention will be apparentfrom the following description, with its appended claims, and theattached drawings.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWING

[0013]FIG. 1 is an exploded view of a drive system in accordance withone embodiment of the invention;

[0014]FIG. 2 is a sectional view of the system 10 after it is assembled;

[0015]FIG. 3 is a perspective view of the assembled drive system withparts;

[0016]FIG. 3A is an enlarged view taken on line 3A of FIG. 3;

[0017]FIG. 4 is a partially exploded view, illustrating the circuitboard before it is mounted on a brush housing;

[0018]FIG. 5 illustrates the circuit board shown in FIG. 4 mounted onthe brush housing;

[0019]FIG. 6 is an assembled view illustrating the brush housing mountedon the electric motor assembly;

[0020]FIG. 7 is a plan view of the circuit board used in one embodimentof the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0021] Referring now to FIG. 1, a drive system or unit 10 is shown. Thedrive system 10 comprises a drive motor 12 situated in a motor housing14 which receives a rotor 16 comprising a plurality of windings 18. Therotor 16 is mounted on an armature 20 having a drive gear 22 towards anend 20 a of the armature 20. It should be appreciated that the housing14 comprises a pair of permanent magnets 24, which cause the armature 20to rotate when a current is applied to the plurality of windings 18 by acommutator 26 in a manner conventionally known.

[0022] The system or drive unit 10 further comprises a brush housing 28having a pair of brush holders 30 and 32 (FIG. 2) as illustrated inFIGS. 3 and 3A, brush holder 30 is defined by a wall 30 a (FIGS. 3 and3A). Note that the brush holders 30 and 32 receive the brushes 34 and 36which are biased by springs 38 and 40, respectively, towards an axis A(FIG. 2) of armature 20.

[0023] The system or drive unit 10 further comprises the circuit board42 (FIGS. 1 and 7), which comprises a circuit 44 for controllingoperation of the system 10. The circuit 44 is coupled to a plurality ofterminals 46 (FIG. 1) for coupling the circuit 44 to a power source (notshown). The circuit 44 is also coupled to the brushes 34 and 36 bysuitable connectors 70 and 72 (FIG. 4), wires, shunts or the like. Thus,it should be appreciated that the brushes 34 and 36 are not mounteddirectly on the circuit board 42, but rather, are mounted remotely fromthe circuit board 42 in the brush holders 30 and 32. Note that thebrushes 30 and 32 are biased towards the commutator 26 (FIG. 2) tofacilitate transferring current, under control of circuit 44, to thecommutator 26 and to the plurality of windings 18 on rotor 16 in orderto cause the armature 20 to rotate.

[0024] As best illustrated in FIGS. 1 and 2, note that the drive gear 22is a worm gear in the embodiment being described and cooperates with adriven gear 48 that is mounted on a shaft 50 having a second gear 52which cooperates with another gear (not shown) in order to perform work,such as driving a window lift mechanism, seat mechanism or othermechanism, and particularly mechanisms situated in a vehicle. Note thatthe system 10 comprises the gear assembly 54 having a gear housing 56with a receiving area 58, which receives the circuit board 42 asillustrated in FIGS. 2 and 3. The gear assembly 54 further comprises agear cover 60 which is mounted on the gear housing 56 by suitable means,such as a spot weld, screws or the like. Although not shown, it shouldbe appreciated that the gear area 62 defined by the gear housing 56 maycomprise a sealing gasket (not shown) so that the gear area 62 is sealedagainst undesired elements, such as moisture or fluids, when the gearcover 60 is mounted on the housing 56.

[0025] Returning now to FIGS. 2-6, note that the circuit board 42 ismounted on the brush housing 28 with resilient detents 64 (FIG. 2) suchthat it lies in a first plane PL. Note that the first plane PL issituated at predetermined angle B relative to a radial lineperpendicular to the axis A of armature 26. In the embodiment beingdescribed, the predetermined angle is an acute angle greater than 0degrees but less than 10 degrees. It has been found that a predeterminedangle of approximately 7 degrees is particularly advantageous formanufacturability. It has been found that an angle greater than 10degrees makes the assembly of the Hall sensor 66 to the circuit board 42and the assembly of the circuit 44 to the brush housing 28 moredifficult to control and may not easily allow an “easy-to-assemble slipfit between the Hall sensor 66 and the brush housing 28.

[0026] The circuit board 42 further comprises a Hall sensor 66 (FIGS. 3and 3A) that is mounted on the board 42 by conventional means such asdip soldering. Note that the Hall sensor 66 is situated a predeterminedangle C on the board 42 such that it is positioned in operative relationwith armature 26 in order to provide rotational speed information to thecircuit 40. In the embodiment being described, the predetermined angle Cis less than 90 degrees, but it could be greater than 90 degrees, forexample, if the Hall sensor 66 was situated on the opposite side 42A(FIG. 4) of the circuit board 42.

[0027] It is important to note that after the circuit board 42 ismounted on the brush housing 14, the Hall sensor 66 is situated inoperative relationship with the armature 20 so that the Hall sensor 66can sense a rotational speed. This rotational speed is then used bycircuit 44 to control the operation of the electric motor in therotational speed of the gear 52 (FIGS. 1-3).

[0028] Referring to FIGS. 4-6, another embodiment of the invention isshown. In this embodiment, the circuit board 42 is mounted on the brushhousing 28, which already comprises the terminals 46 situated in thebrush housing 28. Note that the brushes 34 and 36 are coupled toterminals 70 and 72, respectively (FIG. 5), which are received inopenings 42A and 42B, respectively of circuit board 42 as bestillustrated in FIG. 5. After the circuit board 42 is mounted on theresilient detent 64 to secure the circuit board 42 to the brush housing28, the brush terminals 70 and 72 are soldered by conventional means,such as dip soldering, to the circuit 40. The output terminals 46, ifthey are originally provided in the brush housing 28, are also solderedto the circuit 44 so that power can be supplied to the circuit 44.

[0029] After the circuit board 42 is mounted on the brush housing 28 andsoldering is completed, the motor housing 14 is mounted on a male member28 a of housing 28 so that the armature 20 is situated in operativerelationship with the Hall sensors 66 and the brushes 34 and 36 becomeoperatively related to the commutator 26 so that current can be providedfrom circuit 44, through brushes 34 and 36, to the commutator 26.

[0030] As mentioned after the circuit board 42 is mounted on housing 28and soldering is complete, the housing 14 comprises a female wall 14 dthat is mounted on a male portion 28 a of housing 28. The housing 28 isthen situated on housing 56 such that the circuit board 42 is receivedin the area 58, as illustrated in FIGS. 2, 3 and 3A. The assembly isthen fastened together with screws 80 (FIG. 1). Although not shown, thesystem 10 may comprise a sealant or gasket as desired so that thecircuit board and electric motor 12 are properly sealed from undesiredelements such as fluids.

[0031] After the system 10 is assembled as illustrated in FIGS. 2 and 3,and mounted in a vehicle, for example, the terminals 46 may be coupledto a power source (not shown) so that when a switch, such as a windowlift switch or seat switch, is actuated, circuit 40 responds byenergizing motor 12 which in turn drives armature 20 to rotate gear 22which drives gear 48 that causes gear 52 to rotate to perform thedesired work.

[0032] Advantageously, this system and method provides means forsituating a circuit board relative to an armature of an electric motorsuch that the circuit board is situated in a plane that is notperpendicular to an access of the armature 20 of the motor 12. Thisfacilitates using conventional housing designs and also may facilitatereducing the need extending armature shafts or otherwise making designchanges required by using conventional designs which mandate that thecircuit board have brushes mounted directly thereon and/or lie in aplane that is perpendicular to an access of the armature 20.

[0033] While the systems and methods herein described, and the forms ofapparatus for carrying these systems and methods into effect, constitutepreferred embodiments of this invention, it is to be understood that theinvention is not limited to these precise methods and forms ofapparatus, and that changes may be made in either without departing fromthe scope of the invention, which is defined in the appended claims.

1. A electrical motor having a shaft, said electrical motor comprising: a motor housing having a pair of permanent magnets situated in opposed relation therein; a rotor situated on said shaft between said pair of permanent magnets; said rotor comprising a plurality of windings situated thereon; a commutator for passing current to said plurality of windings; a printed circuit board comprising a circuit for controlling said motor; said printed circuit board being generally planar and lying in a first plane that bisects said axis to define at least one predetermined angle that is acute; a pair of brushes situated in a brush housing in operative relationship with said commutator; a pair of conductors coupling said pair of brushes to said printed circuit board; and a plurality of terminals situated on said printed circuit board for coupling said circuit to a power source.
 2. The electrical motor as recited in claim 1 wherein said at least one predetermined angle is less than 10 degrees.
 3. The electrical motor as recited in claim 2 wherein said at least one predetermined angle is approximately 7 degrees.
 4. The electrical motor as recited in claim 1 wherein said brush housing is situated remotely from said printed circuit board.
 5. The electrical motor as recited in claim 1 wherein said shaft comprises a magnet situated thereon, said printed circuit board comprises a Hall sensor coupled to said circuit and mounted on said circuit board such that when said circuit board is mounted in operative relationship to said electrical motor, said Hall sensor is situated in operative relationship with said magnet in order to sense a speed of said shaft.
 6. The electrical motor as recited in claim 3 wherein said shaft comprises a magnet situated thereon, said printed circuit board comprises a Hall sensor coupled to said circuit and mounted on said circuit board such that when said circuit board is mounted in operative relationship to said electrical motor, said Hall sensor is situated in operative relationship with said magnet in order to sense a speed of said shaft.
 7. The electrical motor as recited in claim 4 wherein said shaft comprises a magnet situated thereon, said printed circuit board comprises a Hall sensor coupled to said circuit and mounted on said circuit board such that when said circuit board is mounted in operative relationship to said electrical motor, said Hall sensor is situated in operative relationship with said magnet in order to sense a speed of said shaft.
 8. A drive unit comprising: an electrical motor having a shaft having a first gear, said electrical motor comprising: a motor housing having a pair of permanent magnets situated in opposed relation therein; a rotor situated on said shaft between said pair of permanent magnets; said rotor comprising a plurality of windings situated thereon; a commutator for passing current to said plurality of windings; a printed circuit board comprising a circuit for controlling said electrical motor; said printed circuit board being generally planar; a pair of brushes situated in a brush housing in operative relationship with said commutator; a pair of conductors coupling said pair of brushes to said printed circuit board; a plurality of terminals situated on said printed circuit board for coupling said printed circuit board to a power source; a gear housing comprising a second gear rotatably mounted therein and situated in operative relationship to said first gear; and said printed circuit lying in a first plane and being mounted between said motor housing and said gear housing such that said first plane bisects said axis at a predetermined angle.
 9. The drive unit as recited in claim 1 wherein said predetermined angle is greater than zero but less than 10 degrees.
 10. The drive unit as recited in claim 2 wherein said predetermined angle is approximately 7 degrees.
 11. The drive unit as recited in claim 1 wherein said brushes are situated remotely from said printed circuit board.
 12. The drive unit as recited in claim 1 wherein said shaft comprises a magnet situated thereon, said printed circuit board comprises a Hall sensor coupled to said circuit and mounted on said circuit board such that when said circuit board is mounted in operative relationship to said drive unit, said Hall sensor is situated in operative relationship with said magnet in order to sense a speed of said shaft.
 13. The drive unit as recited in claim 1 wherein said brush housing further comprises a circuit board mounting area for receiving said circuit board such that when said brush housing is mounted on said motor housing, said circuit board is oriented at said predetermined angle.
 14. The drive unit as recited in claim 13 wherein said predetermined angle is greater than zero but less than 10 degrees.
 15. The drive unit as recited in claim 15 wherein said predetermined angle is approximately 7 degrees.
 16. The drive unit as recited in claim 9 wherein said brushes are situated in said brush housing remotely from said printed circuit board.
 17. The electrical motor as recited in claim 10 wherein said shaft comprises a magnet situated thereon, said printed circuit board comprises a Hall sensor coupled to said circuit and mounted on said circuit board such that when said circuit board is mounted in operative relationship to said electrical motor, said Hall sensor is situated in operative relationship with said magnet in order to sense a speed of said shaft.
 18. The electrical motor as recited in claim 15 wherein said shaft comprises a magnet situated thereon, said printed circuit board comprises a Hall sensor coupled to said circuit and mounted on said circuit board such that when said circuit board is mounted in operative relationship to said electrical motor, said Hall sensor is situated in operative relationship with said magnet in order to sense a speed of said shaft.
 19. The electrical motor as recited in claim 18 wherein said shaft comprises a magnet situated thereon, said printed circuit board comprises a Hall sensor coupled to said circuit and mounted on said circuit board such that when said circuit board is mounted in operative relationship to said electrical motor, said Hall sensor is situated in operative relationship with said magnet in order to sense a speed of said shaft.
 20. A method for assembling an electrical motor having a shaft comprising an axis, a rotor having a plurality of windings, and a commutator for passing current to the windings, said method comprising the steps of: providing a motor housing having a pair of permanent magnets situated in opposed relation therein; situating said rotor between said pair of permanent magnets; situating a printed circuit board in a first plane that bisects said axis to define a predetermined angle, said printed circuit board comprising a circuit and a plurality of terminals for coupling said circuit to a power source; providing a pair of brushes in a brush housing in operative relationship with said commutator, but remote from said printed circuit board; and coupling said pair of brushes to said printed circuit board.
 21. The method as recited in claim 20 wherein said at least one predetermined angle is less than 10 degrees.
 22. The method as recited in claim 21 wherein said at least one predetermined angle is approximately 7 degrees.
 23. The method as recited in claim 20 wherein said brush housing is situated remotely from said printed circuit board.
 24. The method as recited in claim 20 wherein said shaft comprises a magnet situated thereon, said printed circuit board comprises a Hall sensor coupled to said circuit and mounted on said circuit board such that when said circuit board is mounted in operative relationship to said electrical motor, said Hall sensor is situated in operative relationship with said magnet in order to sense a speed of said shaft. 